S-91251A917 1"-8 x 3 1/4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance from the black-oxide finish extends service life in harsh industrial environments, minimizing maintenance and replacement costs.
• Precise Class 3A thread fit with UNRC coarse threads provides secure, vibration-resistant connections, enhancing assembly integrity and reducing loosening over time.
• High hardness rating (Rockwell C37) offers excellent wear resistance, maintaining thread integrity and drive features through repeated use and high torque applications.
• 3/4" hex drive design allows for easy installation and removal with standard tools, improving efficiency in assembly and maintenance workflows.
• Full threading along the 3 1/4" length ensures consistent grip and load distribution, making it ideal for applications requiring deep engagement and uniform clamping force.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees adherence to industry standards and environmental regulations, supporting sustainable and safe procurement practices.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in heavy-duty industrial settings, such as machinery assembly, automotive systems, and structural frameworks. The 1"-8 coarse thread with a Class 3A fit ensures rapid installation and robust, vibration-resistant fastening, reducing downtime in high-cycle operations. Its fully threaded design and high tensile strength provide uniform stress distribution, preventing joint failure under dynamic loads. The black-oxide surface treatment enhances corrosion resistance, making it suitable for environments exposed to moisture, chemicals, or temperature variations. By combining durability with precise UNRC thread standards, this screw delivers long-term reliability in applications demanding both mechanical integrity and compliance with industrial safety and environmental guidelines.

Specification Summary & Compliance

This socket head cap screw features a 1"-8 coarse UNRC thread with Class 3A fit for high precision and secure fastening. It adheres to ASTM A574 specifications, ensuring consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, supporting environmentally responsible sourcing and use in global industrial markets.